A method of and apparatus for transforming a three color signal into a multi-color signal. A method of transforming a color signal having three color components into a color signal having first through n-th color components, includes: producing a lookup table having signal values of (n-3) of n color components of a color within a three-dimensional color space and reference variables corresponding to the signal values of the (n-3) color components; extracting the reference variables from an input color signal; determining the signal values of the (n-3) color components corresponding to the extracted reference variables from the lookup table; and producing a color signal having n color components using the determined signal values of the (n-3) color components.